Sperm and testicular measurements and sperm cryopreservation in the giraffe (Giraffa)

Abstract

Giraffes are numbered amongst vulnerable mammalian species which are likely to become endangered due to the ongoing population decline. In endangered species, the ex situ biodiversity conservation efforts involve captive breeding, genome resource banking and artificial reproduction using cryopreserved gametes. Determination of the sperm standards and the sensitivity of spermatozoa to freezing are crucial points in such activities. We analysed epididymal sperm retrieved from three captive-bred giraffe males (two Giraffa reticulata, one Giraffa camelopardalis rothschildi) and tested the sensitivity of giraffe sperm to cryopreservation. The basic testicular and sperm morphometric measurements, the sperm functional and morphological assessment and the sperm chromatin structure analysis revealed interindividual differences. The epididymal sperm quality of males G2 and G3 was low, probably due to the long-term health problems in G2, sexual immaturity in G3 and longer period between the death/neutering and the sperm retrieval in both animals. Epididymal sperm of male G1 was subjected to cryopreservation in TRIS-fructose-citric acid media with egg yolk. The tested cryopreservation method was approved as suitable for banking giraffe spermatozoa. In the case of endangered species, euthanized and neutered animals can serve as a source of gametes for genome resource banking.